* {
    margin: 0;
    padding: 0;
    font-family: "Source Code Pro";
    box-sizing: border-box;
}

body {
    width: 100vw;
    background-color: #f2f2f2;
}

li {
    list-style: none;
}

a {
    text-decoration: none;
    color: #353535;
}

.menu {
    width: 100%;
    height: 70px;
    background-color: #fff;
    box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}

.menu .nav {
    width: 1200px;
    height: 100%;
    margin: 0 auto;
}

.menu .nav ul {
    position: relative;
    display: flex;
    justify-content: space-around;
    align-items: center;
    width: 100%;
    height: 100%;
}

.menu .nav ul > li {
    position: relative;
    width: 100%;
    height: 100%;
}
.menu .nav ul > li > a {
    font-size: 16px;
    font-weight: 500;
}
.menu .nav ul > li:hover > a {
    color: #f99;
}
.menu .nav ul > li:hover > a::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(90deg, #f99, #99f);
}

.menu .nav ul > li > a {
    display: block;
    width: 100%;
    height: 100%;
    line-height: 70px;
    text-align: center;
}
.menu .nav ul > li ol {
    width: 100%;
    background-color: #fff;
    box-shadow: 1px 1px 3px rgba(0, 0, 0, 0.2);
    /* 让盒子沿Y轴隐藏 */
    transform: scaleY(0);
    /* 设置中心点 */
    transform-origin: 50% 0;
    /* 过渡变化 */
    transition: all 0.6s;
}
.menu .nav ul > li ol li {
    height: 60px;
    border-bottom: 1px solid rgba(245, 245, 245, 1);
}
.menu .nav ul >li ol li a {
    display: block;
    width: 100%;
    height: 100%;
    line-height: 60px;
    text-align: center;
}
.menu .nav ul >li ol li:hover {
    background-color: rgba(0, 0, 0, 0.03);
}
.menu .nav ul >li ol li:hover a {
    color: #f99;
}
/* 让盒子沿Y轴展示 */
.menu .nav ul >li:hover ol {
    transform: scaleY(1);
}

/* 设置活动线条 */
/*
.menu .nav ul .underline {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 240px;
    height: 3px;
    border-top-left-radius: 2px;
    border-top-right-radius: 2px;
    background-color: #f99;
    transition: all .6s;
    pointer-events: none;
}
.menu .nav ul .underline::before {
    content: "";
    position: absolute;
    top: -10px;
    left: calc(50% - 9px);
    width: 18px;
    height: 10px;
    background-color: inherit;
    clip-path: polygon(0 100%, 50% 0, 100% 100%);
}
.menu .nav ul > li:hover ~ .underline {
    left: 240px;
    background-color: #f99;
}
*/
